Evaluation of a self-prepared cotton thread test (SP-CTT) and the phenol red thread (PRT) test

Yee Man Kwong, Hie Hua Wong

Research output: Journal article publicationJournal articleAcademic researchpeer-review

8 Citations (Scopus)


Two cotton thread tests (a self-prepared cotton thread test (SP-CTT) and the Phenol Red Thread (PRT) test) were performed on 46 dry eye and 37 normal Hong Kong (HK)-Chinese, all subjects being diagnosed by ophthalmologists in a private clinic. The mean SP-CTT value for the dry eye subjects (mean ± SD: 6.2±4.2mm/15s) was significantly lower than that of the normal subjects (8.3±4.3mm/15s). However, no significant difference in the mean PRT value was found between the two groups (dry eye subjects: 10.7±4.5mm/15s; normal subjects; 11.4±4.5mm/15s). The specificity and sensitivity of the SP-CTT were 78.4% and 45.7% when a cut-off value of ≤4mm was used, and 56.8% and 65.2% when the cut-off value was changed to ≤6.5mm. Our results showed that the specificities and sensitivities of both tests were poor when applied to these dry eye patients.
Original languageEnglish
Pages (from-to)11-14
Number of pages4
JournalContact Lens and Anterior Eye
Issue number1
Publication statusPublished - 1 Jan 1998


  • Chinese
  • Cotton thread test
  • Dry eye
  • Phenol red thread test specificity
  • Sensitivity

ASJC Scopus subject areas

  • Ophthalmology
  • Optometry


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